1. Field of the Invention
This invention relates to an apparatus for stacking flat objects, preferably double bags which have been severed by hot-wire welding from a tubular web or doubled web of plastic and have opening-defining edges adjacent to the center lines of such double bags, which apparatus comprises a wicketer that comprises spokelike radial feeding arms, which are secured to and angularly spaced around a rotatably mounted horizontal shaft and are arranged in pairs of juxtaposed arms spaced along said shaft and are provided with means, preferably suction nozzles, for retaining the objects on said arms, and which apparatus also comprises interchangeable stacking pallets, which are adapted to receive form the feeding arms the objects to be stacked on said pallet.
2. Description of the Prior Art
Wicketers of the kind described hereinbefore are usually employed to handle bags, which have been intermittently or continuously made and are intermittently or continuously delivered by a conveyor, from which said bags are removed by the wicketer, which then turns said bags through an angle of about 180.degree. and deposits them in a stacking station, in which the bags are stacked. In order to avoid a slipping of the bags in the stack the bags are usually stacked on stacking pallets, which are provided with stacking pins, which extend through bores or holes which have previously been formed in the objects to be stacked or pierce said objects to form such holes. A special problem arises in connection with said stacking operation because the stacks must be moved out of the stacking station and a new stacking pallet for receiving the objects for forming the next stack must be fed to the stacking station and these operations must be performed without a disturbance or interruption of the operation by which the bags are made and are fed to the wicketer.
On principle, it is not possible to suddenly start the movement of a complete stack out of the stacking station because such a sudden start would result in a slipping of the objects in the stack.
From German Patent Specification 19 65 254 it is known that the process of making plastic bags which are to be stacked in a stacking station can be interrupted for some bag-making cycles, during which a stack can be moved away form a stacking deck or a stacking station. But additional control means are required for a performance of some idle cycles and this will also reduce the production rate.
Published German Patent Application 38 11 020 discloses a stacking apparatus which is of the kind described first hereinbefore and comprises a wicketer, by which the bags being delivered are deposited on prestacking support for the time in which a complete stack is carried away, and after said stack has been carried away the objects stacked on said prestacking support are deposited on the stacking support that has been fed to the stacking station in the meantime, whereafter the prestacking support is returned to a waiting position. In that apparatus the prestacking support performs a movement between end points which define a quadrangle. The prestacking on a prestacking support is relatively expensive and involves a considerable additional structural expenditure.